During the latest chapter, Oda leads us to believe that Sabo has died during the Revolutionary Army’s raid on Mary Geoise.
Now, myself and many others believe that this is just simply not the case. It wouldn’t really serve a purpose as a plot device and would quite frankly be very disappointing and lazy storytelling.
In this chapter we see a panel where Blackbeard wants to go to Mary Geoise, or somewhere else, to get something.
We already know the Blackbeard Pirates are collecting powerful Devil Fruits. Furthermore, it was revealed earlier during the Reverie that Vegapunk has made some sort of advancement. Considering that he has previously been successful in manipulating the nature of the Devil Fruits, e.g. putting their powers in inanimate objects, it wouldn’t be inconceivable that Vegapunk has figured out how to extract Devil Fruit powers from their users.
Bear with me, now. Of course, this would be a huge breakthrough, and the World Government wouldn’t let this piece of news slip so easily. The only currently known way for a Devil Fruit power to change ownership is by the death of its current user. Therefore, if the World Government has succeeded in obtaining the Mera Mera no Mi, to everyone else it would effectively mean their user is dead.
This ties back nicely as to why people are reacting with such grief to the news. The World Government are simply showing them that they have obtained Sabo’s Devil Fruit, and so they naturally believe he is dead. The news of this would also explain Blackbeard’s interest, as we know he sought out the Mera Mera no Mi during Dressrosa by sending Burgess to fight for it, and so they are going to try to obtain it yet again.
When that’s all said, I have to give myself some criticism, as I don’t think using the Mera Mera no Mi as a plot device again is much more interesting than another dead brother. However, I think the real giveaway is in Vegapunk’s advancement, which is going to serve the World Government immensely, and an increase in strength might help them keep the world in check now that the order of the Shichibukai is being dismantled.
*Theory by MalFido